This invention concerns a method for processing waste with multistage air classification of light fractions from dried material, as well as a device to implement this method.
The organic material groups in waste are fractions of high calorific value from which fuels may be obtained. The organic material groups consist essentially of light (dispersible) and heavy (granular) fractions which may then be sorted, depending on waste source and application, into coarse (approx. &lt;10 mm), fine (approx. &gt;2 mm-10 mm) and superfine (&lt;2 mm) fractions.
In order to obtain pollutant-free, i.e. the cleanest possible fuels from waste, it is necessary to separate the waste, after suitable pretreatment, into specific material groups and separate out the organic fractions of high calorific value. This is usually achieved using air-classification equipment.
Methods of this kind are described, among others, in
DE-PS 31 05 597 PA0 FP-PS 02 43 747 B1 PA0 U.S. Pat. No. 4,623,515 PA0 U.S. Pat. No. 4,815,668
To separate out the light organic fractions, the known methods require a combination of upstream screening before air classification in order to achieve a sufficiently high degree of separation between the light and heavy particles through air classification of the sorted particle-size groups. Air classification of all particle sizes together results in insufficient degrees of separation. This combined procedure is relatively complex and entails high installation costs of technical implementation.
The task of the invention is to avoid the disadvantages described of high technical complexity and cost for the air classification of light fractions from the waste mixtures and to simplify the air classification process.